New research is the latest to suggest that moderate drinking can negatively impact health. The study found a link between regular alcohol consumption — as little as one to two drinks a day — and decreased brain volume in middle-aged and older people. The brain shrinkage was greater the more someone drank, the study found.
The study was led by researchers from the University of Pennsylvania and the University of Wisconsin–Madison. They analysed data from the UK Biobank, a long-running project that has been tracking the health of more than 35,000 UK residents. As part of the project, volunteers fill out questionnaires about their lifestyle habits, consent to having their genes studied, and undergo high-quality brain scans. Using these scans, the team looked for any connection between reported alcohol use and brain structure.
Our brains naturally shrink in size the older we become, which is one of the reasons our cognitive function declines in later age. There are things that can either accelerate or slow down this process, though, such as exercise. And even a moderate alcohol routine, the researchers concluded, seems to be in the former category.
After controlling for other factors, such as age, body mass index, and head size, they found a negative correlation between alcohol intake and overall brain volume, including in grey matter, the areas of the brain rich in neurons and other cells. Alcohol use was similarly linked to changes in our white matter, where information is relayed between different regions of the brain. As other research has suggested, the authors also found that it didn’t take much alcohol to start seeing these negative health effects.
“[W]e show that the negative associations between alcohol intake and brain macrostructure and microstructure are already apparent in individuals consuming an average of only one to two daily alcohol units, and become stronger as alcohol intake increases,” the authors wrote in their paper, published in Nature Communications earlier this month.
This sort of observational research does have important limitations. Namely, it can’t prove that alcohol use directly causes our brains to shrink; it can only show a correlation between the two. Other evidence, in both animals and humans, has shown that chronic and heavy alcohol use is harmful in both the short and long term, brain included. Though there has been a debate over the exact harms of light-to-moderate drinking, more recent research has suggested that there is no such thing as completely safe alcohol use
The authors say their large sample size is an advantage over past studies and allows them to better understand and quantify the possible toll of regular alcohol use on the brain. Going from zero to one unit of alcohol (about half a beer pint) a day, the authors say, would be equivalent to half a year of brain ageing in the average 50-year-old, for instance, but it jumps to two years for someone going from one to two units of alcohol (a full pint) per day. And for those drinking four or more drinks a day, their brains may age prematurely a full decade, relative to someone who doesn’t drink at all.
The findings, the researchers argue, make the case that many of us could stand to tamp down our alcohol consumption, especially if we’re drinking a fair amount already. And like other scientists lately, they also say that public health authorities could be doing more to set a good example.
“These findings contrast with scientific and governmental guidelines on safe drinking limits,” said study author Kranzler, director of the Penn Centre for Studies of Addiction, in a statement. “For example, although the National Institute on Alcohol Abuse and Alcoholism recommends that women consume an average of no more than one drink per day, recommended limits for men are twice that, an amount that exceeds the consumption level associated in the study with decreased brain volume.”